PCR and Gel Electrophoresis: Moving beyond the technique
Allison R. Phillips and Amber L. Robertson
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Download Teachable Unit |
Download Supplemental Materials |
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Exercises |
PCR Cycle (Word) (PDF) |
Answer Keys |
Pre-Lab PCR Key (Word) (PDF) |
Rubrics |
Final Exercise Rubric (Word) (PDF) |
Surveys |
Pre-Survey (Word) PDF) |
| Developer | Allison Phillips and Amber Robertson |
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| Primary Learning Goals | Students will be able to accurately draw each step of PCR and label the temperature of each step, the directionality of the primers, the proper intermediate products, and the final products. Students will be able to make troubleshooting inferences through reflection on the theory of PCR and gel electrophoresis to determine possible problem areas. Students will be able to explain how DNA molecules move through an agarose gel matrix, that they are separated by size and weight, and why DNA moves towards the positive pole. Students will be able to determine the size of a band in an agarose gel by using a DNA ladder. Students will be able to correctly interpret positive and negative controls. Students will be able to design quality PCR primers using bioinformatics databases. Students will be able to analyze data and use the results to support a position for or against GMOs in a case-based presentation. |
| Secondary Learning Goals | Students will understand how scientists ask questions. Students will be able to select and/or design quality reagents for experiments. Students will understand the importance of each step of a reaction or experiment. Students will be able to make conclusions about data and connect technical results with biological and societal relevance. Students will be able to use bioinformatics tools to gather information to aid in experimental design. Students will be able to present scientific information in formal and semi-formal environments to their professors and peers. |
| Scientific Teaching Themes | We felt there is a greater need to develop materials that address the theories behind several techniques used in molecular experiments, in this case the polymerase chain reaction (PCR) and Our teachable unit design used the framework of scientific teaching. We first established the learning goals that the teachable unit was to address and worked to create a diverse group of active learning exercises to achieve these goals. Multiple methods of assessment and evaluation were used and were based directly on the learning goals. The learning goals were divided into broad and specific learning goals. The broad learning goals addressed fundamental scientific abilities that have general applicability throughout all science courses and labs. These include things like experimental design, gathering, analyzing, and presentation of data, and troubleshooting experimental procedures. The specific learning goals were more targeted to the techniques and theories behind PCR and gel electrophoresis and were directly measured by the evaluative rubric. |
| Diversity | To address the importance of diversity we acknowledged differences in learning styles and student population in the design of the teachable unit. To do this we incorporated activities that allowed students to learn through visual, tactile, and audible exercises. In addition to the mini-lectures, the students were asked to view animations about PCR and gel electrophoresis and then draw out the cycles of PCR. Group work was used as a tool to help students problem solve during multiple exercises and in using bioinformatics tools. Our exercises used examples of both male and female scientists from diverse backgrounds. Feedback from students revealed the inclusive language enhanced their learning experience. |
| Active Learning | We designed the active learning exercises which were guided by the 5E Instruction Model, which is exlaborated upon in the Teachable Unit. |
| Assessment | Formative and summative assessments were used to evaluate student performance and learning gains. Students were formally graded on the PCR Cycle Sketch, Primer Design Exercise and Final GMO Case-Based Presentations. A rubric was specifically designed to assess student performance on the presentations. Informal comments were provided by instructors for the PCR and Gel Analysis exercises. In addition, students frequently received feedback from instructors as they progressed through the exercises and the unit as a whole. |